Officials revealed the bird was found dead on April 1 by a conservation ranger and was only days away from laying eggs.

Heather Humphreys, the Republic's Minister for Heritage, said the loss of a valuable bird to the breeding programme was a huge blow.

"This is a very serious incident as the killing of this breeding female has effectively put an end to any breeding attempt of this beautiful species in west Galway for at least another five years," she said.

"It is particularly disappointing considering this bird was due to lay eggs shortly."

Officials say poisoning - generally intended to kill foxes or crows but banned since 2010 - remains the greatest threat to the reintroduction of the majestic birds of prey.

They breed from about five years old and seven pairs laid eggs in the wild in 2014. Around 100 birds have been set free.